Apple cider vinegar.
Apple cider vinegar has a broad spectrum of benefits that a simple google search will list. There is one (or two) in particular, however, that is supported by scientific evidence, that I would like to bring to your attention.
It stabilises blood sugar and can increase insulin sensitivity.
Insulin sensitivity is how "sensitive" you are to the food you consume, or in other words, your ability to absorb what you're eating. And so, consuming apple cider vinegar before your first meal, or a meal that may take some breaking down, will help you "get the most" out of it.
In addition, it is a useful tool, especially before a high carbohydrate meal, to help stabilise your blood sugar so you don't have sudden spikes and crashes that often follow large meals.
How to consume it:
If anyone has ever told you to take shots of it, they have mislead you. Firstly, this can "burn" the lining of the oesophagus, and it is also highly acidic in its raw form which is harsh on the digestive system. Instead...
Dilute 2 tablespoons with a few 100ml of water and sip it before the given meal.